When a threaded screw fastener is to be inserted or installed within a particular substrate, the threaded screw fastener must obviously be rotated in order to enable the threaded screw fastener to threadedly engage the substrate material. Accordingly, a rotational drive force must be imparted to the threaded screw fastener. Conventionally, the two most common means for imparting rotational drive forces to threaded screw fasteners is either by means of a hexagonal drive socket implement or tool which is adapted to engage a corresponding hexagonally configured head portion of the fastener, or alternatively, by means of a Phillips head drive socket implement or tool which is adapted to engage a correspondingly configured Phillips head portion of the fastener. Typical threaded screw fasteners, respectively having such a hexagonally configured head portion, or a Phillips head portion, are disclosed within FIGS. 1 and 2. More particularly, a first conventional PRIOR ART threaded fastener is disclosed within FIG. 1 and is generally indicated by the reference character 10. The threaded fastener 10 is seen to comprise a threaded shank portion 12, and a head portion 14. The head portion 14 has a hexagonal cross-sectional configuration, and it is also seen that the hexagonally-configured head portion 14 has a constant depth dimension D, as defined between vertically spaced, horizontally disposed, upper and lower planar surfaces 16,18. As a result of such structure, the hexagonally-configured head portion 14 exhibits a relatively large profile. Alternatively, a second conventional PRIOR ART threaded fastener is disclosed within FIG. 2 and is generally indicated by the reference character 110. The threaded fastener 110 is seen to comprise a similarly threaded shank portion 112, and a head portion 114. The head portion 114 is provided with a substantially X-shaped slotted region 116 which is recessed within the head portion 114 so as to be capable of accommodating a Phillips head drive socket implement or tool, and it is additionally seen that the upper surface 118 of the head portion 114 has a substantially domed configuration which circumferentially slopes downwardly so as to terminate in a relatively thin-dimensioned peripheral surface 120.
While the conventional PRIOR ART threaded fasteners 10,110 normally exhibit satisfactory operational or performance characteristics, the conventional PRIOR ART threaded fasteners 10,110 do in fact exhibit some significant operational drawbacks. For example, different field personnel usually prefer to use a particular one of the two different types of conventional PRIOR ART threaded screw fasteners, and accordingly have suitable drive socket implements or tools for drivingly engaging the head portions of the particular threaded screw fasteners. The obvious problem with the existence or availability of the two different types of conventional PRIOR ART threaded screw fasteners resides in the manufacture and distribution of such threaded screw fasteners, that is, the threaded screw fastener manufacturers need to manufacture or fabricate the two different types of threaded screw fasteners, they need to stock the two different types of threaded screw fasteners in their available inventories, and they need to maintain proper and appropriate records in connection with the distribution of such different types of threaded screw fasteners to different distribution centers or end-use customers. Similar manufacturing, fabrication, inventory, distribution, and logistical problems correspondingly exist in connection with the availability of the suitable drive socket implements or tools for drivingly engaging the head portions of the different threaded screw fasteners. A need therefore exists in the art for a new and improved threaded screw fastener which is provided with a head portion that has integrally incorporated therein both hexagonal and Phillips head structure so as to be capable of being rotationally driven by means of a new and improved single drive socket implement or tool which likewise has integrally incorporated therein structure which is uniquely adapted to engage either one of the hexagonal and Phillips head structures integrally disposed upon the head portion of the threaded screw fastener.
In addition, it is seen that the vertically spaced, horizontally disposed, upper and lower planar surfaces 16,18, together with the six, vertically oriented side surfaces or facets 20 of the head portion 14, define a plurality of vertically spaced, upper and lower peripheral edge portions 22, wherein each one of the upper and lower peripheral edge portions 22 defines, includes, or comprises a 90° angle. It is also seen that adjacent pairs of the side surfaces or facets 20,20 define a plurality of vertically oriented edge regions or loci 24 therebetween, whereby the upper and lower termini of the vertically oriented edge regions or loci 24 define sharply pointed corner loci 26. Accordingly, when the threaded screw fasteners 10 are utilized, for example, in connection with the fastening or securing of waterproof or environmental membranes to underlying roof decking assemblies, the peripheral edge portions 22, defined between the vertically oriented side surfaces or facets 20 and the upper planar surface 16, as well as the upper corner loci 26 disposed within the plane of the upper planar surface 16, present sharply configured structures.
It has been found that such sharply configured structures can effectively cut or pierce the waterproof or environmental membranes when, for example, the waterproof or environmental membranes are forced into contact with the fastener head portions 14 as a result of, for example, workmen walking upon the upper surface portion of the roof decking assembly. Accordingly, once the waterproof or environmental membranes are cut or pierced, the waterproof or environmental membranes tend to undergo further structural deterioration, such as, for example, propagated shredding or tearing, particularly under high-wind lift force conditions, thereby effectively compromising the structural integrity of the waterproof or environmental membranes and of course the protective properties of the waterproof or environmental membranes with respect to the underlying roof decking and insulation substrates. This is obviously not a desirable situation from the viewpoint of installing a proper, environmentally protected roof decking system. A need therefore exists in the art for a new and improved threaded screw fastener which is provided with a head portion that not only has integrally incorporated therein both hexagonal and Phillips head structure so as to be capable of being rotationally driven by means of a single drive socket implement or tool which likewise has integrally incorporated therein structure which is uniquely adapted to engage either one of the hexagonal and Phillips head structures integrally disposed upon the head portion of the screw fastener, but in addition exhibits a relatively low profile.
Continuing further, and with reference now being made to FIGS. 3 and 4, an additional conventional PRIOR ART threaded screw fastener is partially disclosed and is generally indicated by the reference character 210. The threaded screw fastener 210 comprises a shank portion 212 upon which a plurality of buttress-type threads 214 are formed. As can best be seen or appreciated from FIG. 4, each one of the conventional buttress-type threads 214 is seen to comprise a slightly inclined rearward flank surface 216 and a significantly inclined forward flank surface 218, a predetermined thread pitch P, as measured between the same points of successive thread crest portions 220, and a predetermined spacing S as determined between the root region of the rearward flank surface 216 of a particular thread and the root region of the forward flank surface 218 of the next or successive thread. As is well-known in the art or industry, the rear flank surface 216, as well as the pitch P, play critical roles in, or effectively determine, the pull-out resistance characteristics or properties of the fastener 210, while the forward flank surface 218, and the spacing S, likewise play critical roles in, or effectively determine, the installation or insertion torque characteristics or properties of the fastener 210. As is further well-known in the art of industry, the ideal or perfectly designed fastener will exhibit relatively high pull-out resistance characteristics or properties, while concomitantly exhibiting relatively low installation or insertion torque characteristics or properties. Unfortunately, conventional or PRIOR ART fasteners, such as, for example, the fastener 210, as disclosed within FIGS. 3 and 4 and characterized by means of the conventional or PRIOR ART buttress thread structure, cannot effectively simultaneously achieve the aforenoted relatively high pull-out resistance characteristics or properties and the relatively low insertion or installation torque characteristics or properties.
More particularly, in order to effectively increase the pull-out resistance characteristics or properties of the threaded screw fastener 210, the diametrical extent of the threaded screw fastener 210 would have to be increased, that is, the external diametrical dimensions or extents of both the shank portion 212 and the threads 214 as determined by means of the crest portions 220 thereof. Increasing the diametrical dimension or extent of the threaded screw fastener 210, however, is not desirable or viable for several reasons. Firstly, for example, increasing the diametrical dimension or extent of the threaded screw fastener 210 obviously increases the amount of material that is required to be structurally incorporated within each fastener 210, and therefore the manufacturing or fabrication costs per fastener are correspondingly increased. In addition, or secondly, increasing the diametrical dimension or extent of the threaded screw fastener 210 also serves to increase the installation or insertion torque characteristics or properties of the fastener 210, which, of course, is precisely the opposite objective that is sought to be achieved in connection with the threaded screw fastener 210. Viewed from an opposite point of view, if, for example, the diametrical dimension or extent of the threaded screw fastener 210 was decreased so as to effectively reduce the torque installation or insertion characteristics or properties of the threaded screw fastener 210, then the pull-out resistance characteristics or properties of the threaded screw fastener 210 would be correspondingly reduced, which, again, is precisely the opposite objective that is sought to be achieved in connection with the threaded screw fastener 210. A need therefore exists in the art for a new and improved threaded screw fastener which can simultaneously achieve both enhanced pull-out resistance characteristics or properties, and reduced installation or insertion torque characteristics or properties, while also retaining manufacturing or fabrication costs at a viable or cost-effective level.